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package org.apache.juneau.http;

/**
 * Represents a parsed <l>WWW-Authenticate </l> HTTP response header.
 * 
 * <p>
 * Indicates the authentication scheme that should be used to access the requested entity.
 * 
 * <h5 class='figure'>Example</h5>
 * <p class='bcode'>
 * 	WWW-Authenticate: Basic
 * </p>
 * 
 * <h5 class='topic'>RFC2616 Specification</h5>
 * 
 * The WWW-Authenticate response-header field MUST be included in 401 (Unauthorized) response messages.
 * The field value consists of at least one challenge that indicates the authentication scheme(s) and parameters
 * applicable to the Request-URI.
 * 
 * <p class='bcode'>
 * 	WWW-Authenticate  = "WWW-Authenticate" ":" 1#challenge
 * </p>
 * 
 * <p>
 * The HTTP access authentication process is described in "HTTP Authentication: Basic and Digest Access Authentication".
 * User agents are advised to take special care in parsing the WWW-Authenticate field value as it might contain more
 * than one challenge, or if more than one WWW-Authenticate header field is provided, the contents of a challenge
 * itself can contain a comma-separated list of authentication parameters.
 * 
 * <h5 class='section'>See Also:</h5>
 * <ul class='doctree'>
 * 	<li class='extlink'><a class='doclink' href='https://www.w3.org/Protocols/rfc2616/rfc2616.html'>Hypertext Transfer Protocol -- HTTP/1.1</a>
 * </ul>
 */
public final class WwwAuthenticate extends HeaderString {

	/**
	 * Returns a parsed <code>WWW-Authenticate</code> header.
	 * 
	 * @param value The <code>WWW-Authenticate</code> header string.
	 * @return The parsed <code>WWW-Authenticate</code> header, or <jk>null</jk> if the string was null.
	 */
	public static WwwAuthenticate forString(String value) {
		if (value == null)
			return null;
		return new WwwAuthenticate(value);
	}

	private WwwAuthenticate(String value) {
		super(value);
	}
}
